I'd skip the exo terra and go with an AP pvc enclsoure. The exo-terras aren't that great at holding temps due to the all glass sides. I use them for planted terrariums (frogs and geckos) but those species don't require the higher warm side temps that BPs do. If you do decide to go with an exo terra, I would suggust the largest you can get (3'x2' footprint) and maybe the one that is 2' high. You would need to insulate the sides (maybe use pvc or insulation board) on the 3 sides excluding the front. You would need to use a heat pad and possibly a CHE to maintain good hot spot and ambient temps...Just don't place the CHE over glass, it would need to go over the screen and you would most likely need to purchase glass or plexiglass panels to cover the rest of the screen top to hold in humidity.
I would personally go with an Animal Plastics cage as I think it would end up costing you the same or less (considering the modifications you'd need to make on the exo). The PVC cages are also lighter and easier to move, which is a huge plus. I have the biggest exo (3'x2'x3') and it is a beast to move empty. I don't even want to think about having to move it fully planted.